Have you had herbicide applied to your lawn or gardens? Have your neighbors? 

This could be a sprayed herbicide on weeds or a granular or liquid herbicide applied directly to lawn (usually as a pre-emergent). 

I am concerned about the growth on your hydrangea. 

Can you send a few more photos that show the entire tree or shrub?

Since your plants aren't in the lawn, it seems less likely that they are being damaged by herbicide. I might pull in a colleague who has more experience with herbicide damage than me and ask their opinion.

Are you watering the hydrangea? What side of the house is it on? Is there landscape fabric at the base of the plant?

First, the cherry tree. I don't think you sent me a second photo. Weeping cherries are often short-lived. They are frequently grafted onto the trunk of a non-weeping tree. You might see weeping branches as well as branches growing straight up. The upright branches should be removed or they will overtake the weeping form. 

I am concerned about the hydrangea and its siting. I think the location next to the house is not ideal. It is probably suffering from heat bouncing off the building and rocks, lack of water, and the Preen may be effecting it. If there is landscape fabric under the rocks, it can be detrimental to the roots of the hydrangea. It can be hard to differentiate between nutrient deficiencies and herbicide damage. It may be be nutrient deficient because the roots are suffering and cannot pull the nutrients into the plant. 

I asked my colleague Caitlin Splawski who is more familiar with pesticides.  Here is her feedback:

I don't think Preen would do that, so this could be from a combo of fertilizer misapplication and lack of water. Although that hydrangea has some really funky growth that looks very much like herbicide damage, and nutrient toxicity can be a symptom of herbicide injury. Herbicides can drift from other sites, not sure of their proximity to farm fields, but that can happen. Also, the way water is leaching from the lawn could be dosing the plants through their roots, they should contact their lawn service for more information for sure.

Here's a link with information about preventing herbicide injury. 

"Many preemergence herbicides are tolerated by established woody plants, especially plants with healthy, well-developed root systems. Damage sometimes occurs if preemergence herbicide is applied at high rates, incorporated too deeply into the root zone, is not labeled for the site, or is applied near poorly rooted young plants or shallow-rooted plants." Source and more information about Preen causing damage. 

I would recommend that you investigate what is going on in their beds as far as how they accept and drain water. Is it coming from the lawn? Is the tree getting any rain water? How much and how often?